Investigators looked at information from four large studies that followed children into adulthood in an effort to determine if childhood obesity necessarily leads to an increase in heart and stroke risk as an adult.

They found little evidence of a long-term health impact associated with early obesity among adults who had been able to get back to a normal weight.

While this finding was encouraging, there was a not-so-surprising discouraging finding as well: Most obese children became obese adults, and their risk for heart attacks, stroke, and diabetes was much higher than their normal-weight counterparts.

"As far as we know this is the first time it has been shown that obesity as early as the age of 3 may not have long-term health consequences in children who are able to lose the weight before adulthood," study researcher Markus Juonala, MD, PhD, of the Turku University Hospital in Finland, tells WebMD.

"But only about 20% of obese children were normal weight as adults, compared to about 85% of children who were not overweight or obese," Juonala says. "This illustrates the importance of doing as much as we can to prevent childhood obesity."

Benefits of Reaching a Healthy Weight in Childhood

Researchers examined data on about 6,300 people who took part in four studies. The study participants were followed for an average of 23 years from childhood to adulthood. Obesity was defined as having a body mass index (BMI) of 30 or greater.

Body mass index is a calculation that divides your weight by your height to estimate your amount of body fat. In children, body mass index is compared to other children the same age and sex and expressed as a percentile.